Corundum

Sapphire

Refractive Index: 1.7600–1.7681
Abbe Number: 72.3–73.0
Crystal System: Uniaxial
Formation: Natural
Dispersion Data: Measured (published fit)
Fits: 1

Refraction Fits

Fit #1

Sellmeier

$n_{ω}$ ordinary

n_{ω}

= 1.7681

V_{ω}

= 72.3

n_{ω}^{2} = 1 + \frac{1.431349 λ ^{2}}{λ ^{2} - 0.00528} + \frac{0.650547 λ ^{2}}{λ ^{2} - 0.014238} + \frac{5.341402 λ ^{2}}{λ ^{2} - 3.250 e + 2}

$n_{ε}$ extraordinary

n_{ε}

= 1.7600

V_{ε}

= 73.0

n_{ε}^{2} = 1 + \frac{1.503976 λ ^{2}}{λ ^{2} - 0.00548} + \frac{0.550691 λ ^{2}}{λ ^{2} - 0.014799} + \frac{6.592738 λ ^{2}}{λ ^{2} - 4.029 e + 2}

Absorption Specimens

Cambodia, Battamberg, Pailin

Myanmar, Mandalay Division, Mogok

Myanmar, Mandalay Division, Mogok

Myanmar, Mandalay Division, Mogok (Gemological observations suggest this sapphire could be either of Myanmar or Sri Lanka origin)

Myanmar, Mandalay Division, Mogok (Kyauk-Pyat-Thet)

Myanmar, Mandalay Division, Mogok (Kyauk-Pyat-Thet)

Myanmar, Mandalay Division, Mogok (Kyauk-Pyat-Thet)

Myanmar, Mandalay Division, Mogok, Gemological observations suggest this sapphire could be either of Myanmar or Sri Lanka origin

Tanzania, Tanga Region, Umba Valley

Tanzania, Tanga Region, Umba Valley ( Gemological observations suggest this sapphire could be either of Madagascar or Tanzania origin)

Thailand, Chanthaburi Province

Thailand, Chanthaburi Province

Thailand, Chanthaburi Province

Thailand, Chanthaburi Province

Thailand, Chanthaburi Province

Thailand, Chanthaburi Province

Thailand, Chanthaburi Province

Thailand, Chanthaburi Province

Thailand, Chanthaburi Province, Tha Mai (Bang Kha Cha)

Thailand, Chanthaburi Province, Tha Mai (Bang Kha Cha)

Thailand, Chanthaburi Province, Tha Mai (Bang Kha Cha)

Thailand, Kanchanaburi Province, Bo Phloi